CHE-01
ASSIGNMENT BOOKLET
Bachelor’s Degree Programme (B.Sc.)
ATOMS AND MOLECULES
(Valid from 1st January, 2015 to 31st December, 2015)
Please Note
 You can take electives (56 to 64 credits) from a minimum of TWO and a
maximum of FOUR science disciplines, viz. Physics, Chemistry, Life
Sciences and Mathematics.
 You can opt for elective courses worth a MINIMUM OF 8 CREDITS and a
MAXIMUM OF 48 CREDITS from any of these four disciplines.
 At least 25% of the total credits that you register for in the elective
courses from Life Sciences, Chemistry and Physics disciplines must be
from the laboratory courses. For example, if you opt for a total of 64
credits of electives in these 3 disciplines, at least 16 credits should be
from lab courses.
 You cannot appear in the Term-End Examination of any course without
registering for the course. Otherwise, your result will not be declared
and the onus will be on you.
School of Sciences
Indira Gandhi National Open University
Maidan Garhi, New Delhi-110068
(2015)
1
Dear Student,
We hope, you are familiar with the system of evaluation to be followed for the Bachelor’s Degree
Programme. At this stage you may probably like to re-read the section on assignments in the Programme
Guide that we sent you after your enrolment. A weightage of 30 per cent, as you are aware, has been
earmarked for continuous evaluation, which would consist of one tutor-marked assignment. The
assignment is based on Blocks 1 and 2.
Instructions for Formatting Your Assignments
Before attempting the assignments, please read the following instructions carefully:
1. On top of the first page of your answer sheet, please write the details exactly in the following
format:
ENROLMENT NO.:.….………………….………
NAME:…………..…………………
ADDRESS:.…..............………………
………………………………
………………………………
COURSE CODE
: …..........................…………
COURSE TITLE
: …..........................…………
ASSIGNMENT NO.: …..........................…………
STUDY CENTRE : …..........................…………
(NAME AND CODE)
DATE:..………………………….
PLEASE FOLLOW THE ABOVE FORMAT STRICTLY TO FACILITATE EVALUATION AND
TO AVOID DELAY.
2. Use only foolscap size writing paper (but not of very thin variety) for writing your answers.
3. Leave 4 cm margin on the left, top and bottom of your answer sheet.
4. Your answers should be precise.
5. While writing answers, clearly indicate the Question No. and part of the question being solved.
6. Please note that:
i)
The Assignment is valid from 1st January, 2015 to 31st December, 2015.
ii)
The response to this assignment is to be submitted to the Study Centre Coordinator within
eight weeks of the receipt of this booklet in order to get the feedback and comments on the
evaluated assignment.
iii) In any case, you have to submit the assignment response before appearing in the term end
examination.
7. We strongly suggest that you should retain a copy of your assignment responses.
Wishing you all good luck.
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Tutor Marked Assignment
Atoms and Molecules
Course Code: CHE-01
Assignment Code: CHE-01/TMA/2015
Maximum Marks: 100
Attempt all the questions. Each question carries 10 marks.
Use the following data:
Permittivity in vacuum = 8.854 × 10-12 C2 N-1 m-2
Planck’s constant = 6.626 × 10-34 J s
Mass of electron = 9.109 × 10-31 kg
Magnitude of the charge on the electron = 1.602 × 10-19 C
Avogadro constant = 6.022 × 1023 mol-1
Velocity of light = 2.998 × 108 m s-1
1.
Assume that the electron in He+ ion is excited to the second orbit (n = 2). Calculate the
following:
(i)
the radius of the orbit
(ii)
the velocity of the electron
(10)
(iii) the potential energy of the electron, and
(iv)
the kinetic energy of the electron.
Hint: Use equations derived for hydrogen atom in Unit 1.
2.
(a)
Using Table 2.2 of Unit 2, explain the shapes of 1s and 2py orbitals of an atom
with one electron.
(b)
3.
(5)
Calculate the de Broglie wavelength of Li+ ion, if it moves with the velocity of
2  104 m s1. Assume that the mass of Li+ ion is equal to two mass of Li atom. (5)
State the reason for the following:
(10)
(i)
HI has more covalent character than HCl.
(ii)
Ionic compounds are more soluble in water than benzene.
(iii) The radius of S2 ion is larger than the radius of Cl ion.
(iv) In NaBr crystal, each ion is octahedrally surrounded by ions of opposite charge.
(v)
In HF, the experimental bond length value is less than the sum of covalent radii.
4. Based on molecular orbital theory, draw the energy patterns for NO+ ion and CO
molecule. Between these two, point out the similarities with respect to bond order
and magnetic character and, the dissimilarity with respect to energy pattern of
orbitals.
5. (a)
(b)
Explain the shape of BeF2 molecule based on the hybridization concept and
VSEPR theory.
(10)
(5)
Identify the type of hybridization of the carbon atoms in the following compound:
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CH2 = CHCOCH3
(5)
Also predict the carbon-carbon and carbon-hydrogen bond length using Table 4.4.
6. The inter atomic distance of 14N16O molecule is 115.1 pm. Calculate
(10)
(i)
its reduced mass,
(ii)
its moment of inertia,
(iii)
the wave number of the line corresponding to lowest absorption in m1 Unit, and
(iv)
the energy in m1 unit for the transition J = 2 to J = 3.
7. (a)
Write down the enantiomers of a compound having two asymmetric carbon atom
each having  CH3,  OH and Br groups. Write down a structure for the
meso form.
(5)
(b)
You are given a gaseous substance. Suggest an experimental method to find out
whether it is polar or nonpolar. Discuss the steps to be used in this method.
(5)
8. Explain the following terms:
(i)
Mass defect
(ii)
Binding energy per nucleus
(iii)
Binding energy per nucleon
(iv)
Nuclear fusion
(v)
Nuclear fission
9. (a)
(b)
10. (a)
(b)
(10)
The molar extinction coefficient of a compound, X, at 370 nm wave length
is 250 m2 mol1. Its solutions of concentration 7.5  102 mol m3 is taken
in a cell of thickness 0.010 m. Find the ratio of the intensity of transmitted
radiation to the intensity of the incident radiation.
(5)
For 12C 16O, the fundamental frequency is 2143 cm1. Calculate the fundamental
frequency of 14C 16O.
(5)
For 214Bi, the half-life period is 19.7 minutes. Calculate the radioactive decay
constant. Also calculate how much of 1 gram sample of 214Bi will remain after
78.4 minutes.
(5)
Explain the following using an example in each case:
(5)
i)
the effect of inter molecular hydrogen bonding on the infrared spectra
of the compounds, and
ii)
the effect of conjugation on π →π* transition.
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